Application of comprehensive geophysical prospecting method in uplift geothermal field

In this paper, the authors have taken Xiangshanwan geothermal field in Xiamen as an example to detect the fault related geothermal water enrichment areas and determine the optimum borehole position based the Geophysical anomaly, combined with the comprehensive geophysical prospecting method of Controlled Source Audio-frequency Magneto Tellurics (CSAMT), joint resistivity profiling and resistivity sounding. The results show that the CSAMT method is efficient and reliable to prospect the spatial distribution characteristics of fault structures in the study area, and it can be used to determine the possible areas of geothermal reservoir. The joint resistivity profiling and resistivity sounding are arranged vertically along the strike of the inferred fault structures to verify the fault structures inferred by the CSAMT method, which would further determine the occurrence of the fault structures in the geothermal water enrichment section and eliminate the multiple interpretational nature of geophysical prospecting method. Finally, the cross region formed by the hanging wall of multiple groups of fault structures is selected as the best borehole target area for geothermal geological drilling. The drilling results show that the single well yield is about 41.76 m³/h, and water temperature is of 52 ℃, with the total soluble solid of 6 183.19 mg/L and the water type of Cl-Na in Xiangshanwan geothermal field.